TREND Dual Streaming H.264 Multiplex 8CH/16CH Network DVR, User Manual

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8. Appendix
Appendix A-HDD Capacity Estimate
1) Calculate the maximum capacity of the build-in hard disk.

Timing Recording:
Step 1: Calculate the maximum capacity of the hard disk needed in selected channel per hour,
suppose as Si (MByte) (i is the channel number), and suppose the bit rate of the channel selected
as D (Kbit/s). The formula of calculation is:
Si =
（
D*3600
）
/
（
8*1024
）
= D * 0.439453125 MB
Step 2: Confirm the storage time length, suppose as T hours. The total maximum capacity of the
hard disk needed in selected channel for T hours, suppose as St is:
St = T * S1
Step 3: Confirm the total numbers of the channels, suppose as n. The total maximum capacity of
the hard disk needed, suppose as Sc is:
Sc = S1 + S2 + … + Sn
 Alarm Recording
Suppose the rate of alarming as α%. The capacity of the hard disk needed in alarm recording
supposed as Sa is:
Sa = Sc * α%
2) Calculate the compression bit rate for recording T hours.
 Timing Recording
Step 1: Suppose the capacity of the hard disk as S, the total numbers of the channel as n. The
capacity of hard disk needed per channel supposed as Di is:
Di = S / n
Step 2: Suppose the total recording time as T hours. The capacity of the hard disk needed per hour
per channel supposed as Dt is:
Dt = Di / T
Step 3: The bit rate of all the channels supposed as Dc is:
Dc = Dt *
（
8*1024
）
/ 3600 = Dt * 2.2756
（
Kbit/s
）
Alarm Recording
Step 1: Suppose the rate of alarming as α%, capacity of hard disk as S, the total numbers of the
channel as n. The capacity of hard disk needed per channel supposed as Di is:
Di = （ S / n ） * α%
Step 2: Suppose the time length of recording as T (hours). The capacity of hard disk needed per
hour per channel supposed as Dt is:
Dt = Di / T
Step 3: The bit rate of all channels supposed as Dc is:
Dc = Dt *
（
8*1024
）
/ 3600 = Dt * 2.2756
（
Kbit/s
）
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